The present invention relates to a telecommunications system using an intelligent network (IN) architecture, and in particular to the control of a peripheral in such a network.
In conventional public switched networks (PSTNs) the functions the network is able to perform depend on the design of the switch which handles basic call-routing. Introducing any new functionality requires the switch to be redesigned, with the provision of new software and possibly also new hardware. For a large network this process can take one or more years. As PSTNs are required to provided a rapidly growing range of services to users, this type of delay in service provision becomes increasingly unacceptable.
Intelligent networks (IN's) have been developed to address the problem of the relative inflexibility of conventional networks. As described in the paper by T W Abernethy and A C Munday, "Intelligent networks, standards and services" BT Technol J Vol 13 No. 2 April 1995, in the intelligent network the control of the basic call routing is carried out at a service switching point (SSP) and is kept functionally separate from the control of call progression by a service control point (SCP). The service control point is also able to access functions provided by an intelligent peripheral (IP). An intelligent peripheral might be equipped, for example, to play pre-recorded announcements to a subscriber. To ensure that the interworking of networks and components of different operators and suppliers is possible, the architecture and protocols of the intelligent network are required to conform to internationally agreed standards. The need to conform to these standards might however tend to negate the very flexibility which the IN architecture was intended to provide. For example, BT has developed and deployed in the UK PSTN a voice messaging service known as CALL MINDER (TM). It would be desirable to incorporate this service on an intelligent peripheral within an IN system. The Call Minder functions however do not correspond to either of the two classes of IP functions which the relevant standards provide for.